Process of treating petroleum still gases



Patentedilune 24, 1924.

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BENJAMIN r. BROOKS, or BAYS'IDE, imw' onx, assrenon rocmnnnom'cnnmcancomm, A CORPORATION or wnsr. VIRGINIA.

PROCESS. on 'rnnn'rrive PETROLEUM STILL GASES.

No Drawing. Original application filed August 21,1919, Serial No.818,860. Divided and this application Y filed December 14, 1920. SerialNo. 430,785.

To allwhomz'tmay concern: I 4

Be it known that I, BENJAMIN T. BROOKS, a citizen of the United States,and a resident of Bayside, in the county of Queens, State of New York,have invented certain new and useful- Improvements in Processes ofTreating Petroleum Still Gases, of which the following is aspecification. This application is a division of my copendingapplication No. 318,860, filed Auggust 21, 1919. i

The present invention relates to a new and useful method of treatingpetroleum still gases. When crudepetroleums are distilledrelativelylarge volumes of gas are given off toward the end of thedistillation, particularly in the type of stills known as cokingstillsfl The gas referred to passes through the condensers Where oilvapors are condensed and removed and then the gas passes to the open airto suitable receivers, or, as is usually the case, is burned as fuel.This gas has a peculiar and characteristic composition. It more closelyresembles coal retort gas rather than the ordinary oil gas made bycracking oil in hot tubes, heated brick chambers and the like. Whereasthe latter gas usually contains forty to fifty per cent of illuminants,still gas like coal gas usually contains ten per cent or less by volumeof illuminants.

as it issues fromthe stills frequentlycontains conspicuous quantities ofammonia whereas ordinary oil gas is. free from this substance. Howevercoal gas and oil gas are both richer in aromatic hydrocarbonshypochlorous acid in dilute aqueous solution to form the correspondingchlorhydrins. It is also fairly obvious that agitation and increasedpressures will facilitate the solution of these olefines in the aqueoussolution. I find however that the practiceof these simple expedients isnot sufficient in the case of still gas to effect economicoperation,'that Like coal gas, still gas,

is to say the characteristic olefine content of still gas is so smallthat'even by the use of pressures of 100 or-150 lbs. per square inch,the absorption of the olefines is too slow for practical or usefulresults. I have overcome this difliculty'by absorbing the olefines in a.

solvent having greater solve'nt power for the gaseous olefines thanwater. Thus I find that the solubility of ethylene in'the gasolinefraction 100-110 is about twelve times as great as in water at ordinaryatmospheric temperature and pressure. This may advantageously be doneunder a gas pressureof about 75 to 150 lbs. pressure thus diminishingthe loss of solvent by evaporation and accelerating the solution of theolefines. This solvent when immiscible' in water as in thepreferred-form of my invention, also serves theimportant purpose oftaking up in solution and thus extracting continually the chlorhydrin,or chlorhydrins from the aqueous solution. Hypochlorous acid may passinto the solvent layer to some extent and form chlorhydrins in thesubstantially non aqueous phase or layerk However I do not limit myselfto this explanation but note as a fact that when an immiscible solventbenzol, gasoline or kerosene, for example, is employed a large part ofthe chlorhydrin is found at theend of the operation in the solventlayer. has the practical advantage that more chlorhydrin can be producedin one operation than when aqueous solutions alone are employed. This isprobably accounted for not only by the'solvent effect of the organicsolvent'in removing the olefines from the gas This (dilute with respectto olefines) and thus 1 l rendering them. accessible to the'hypochlorous acid, but also by the fact that in aqueous salt solutions theformation 'of chlorhydrins is very much retarded when the concentrationof chlorhydrins isequal to about five or,

acid is prepared by any of the well known methods, for example theactionof chlorine water on a heavy metal oxide, the action of chlorineon an aqueous solution of a carbonate, bicarbonate, borate or other saltof a weak acid, or the action of a weak acid such I:

as carbonic acid or boric acid 'on a soluble hypochlorite'. ParticularlyI prefer to empreformed olefine solution made by dissolving the-normallypochlorous acid and which 7 process which comprises subjecting asolugaseous olefines contained in petroleum still gas of about 10 to 12%olefine content, in an organic solvent which is substantially notaffected by aqueous hyis completely miscible with the chlorhydrins.

2. In the manufacture of chlorhydrins the step which comprisescontacting a solu-' tion of olefines in a petroleum distillate boilingbetween 150 and 180 (1, with an aqueous hypochlorousacid solution.

' In the manufacture of 'chlorhydrins the sure to the'action of anaqueous solution of hypochlorous acid.

4. In themanufacture of chlorhydrins the step which comprises contactinga solution of olefinesin 011 a petroleum distillate of which the majorpart boils between 100 and180 C. with aqueous hypochlorous acid.

In testimony whereof, Iliave signed this specification;

BENJAMIN T. BROOKS.

